mcs/mcs/delegate.cs

   1 //
   2 // delegate.cs: Delegate Handler
   3 //
   4 // Authors:
   5 //     Ravi Pratap (ravi@ximian.com)
   6 //     Miguel de Icaza (miguel@ximian.com)
   7 //     Marek Safar (marek.safar@gmail.com)
   8 //
   9 // Dual licensed under the terms of the MIT X11 or GNU GPL
  10 //
  11 // Copyright 2001 Ximian, Inc (http://www.ximian.com)
  12 // Copyright 2003-2009 Novell, Inc (http://www.novell.com)
  13 //
  14
  15 using System;
  16
  17 #if STATIC
  18 using IKVM.Reflection;
  19 using IKVM.Reflection.Emit;
  20 #else
  21 using System.Reflection;
  22 using System.Reflection.Emit;
  23 #endif
  24
  25 namespace Mono.CSharp {
  26
  27         //
  28         // Delegate container implementation
  29         //
  30         public class Delegate : TypeContainer, IParametersMember
  31         {
  32                 FullNamedExpression ReturnType;
  33                 readonly ParametersCompiled parameters;
  34
  35                 Constructor Constructor;
  36                 Method InvokeBuilder;
  37                 Method BeginInvokeBuilder;
  38                 Method EndInvokeBuilder;
  39
  40                 static readonly string[] attribute_targets = new string [] { "type", "return" };
  41
  42                 public static readonly string InvokeMethodName = "Invoke";
  43
  44                 Expression instance_expr;
  45                 ReturnParameter return_attributes;
  46
  47                 const Modifiers MethodModifiers = Modifiers.PUBLIC | Modifiers.VIRTUAL;
  48
  49                 const Modifiers AllowedModifiers =
  50                         Modifiers.NEW |
  51                         Modifiers.PUBLIC |
  52                         Modifiers.PROTECTED |
  53                         Modifiers.INTERNAL |
  54                         Modifiers.UNSAFE |
  55                         Modifiers.PRIVATE;
  56
  57                 public Delegate (NamespaceEntry ns, DeclSpace parent, FullNamedExpression type,
  58                                  Modifiers mod_flags, MemberName name, ParametersCompiled param_list,
  59                                  Attributes attrs)
  60                         : base (ns, parent, name, attrs, MemberKind.Delegate)
  61
  62                 {
  63                         this.ReturnType = type;
  64                         ModFlags        = ModifiersExtensions.Check (AllowedModifiers, mod_flags,
  65                                                            IsTopLevel ? Modifiers.INTERNAL :
  66                                                            Modifiers.PRIVATE, name.Location, Report);
  67                         parameters      = param_list;
  68                         spec = new TypeSpec (Kind, null, this, null, ModFlags | Modifiers.SEALED);
  69                 }
  70
  71                 #region Properties
  72                 public TypeSpec MemberType {
  73                         get {
  74                                 return ReturnType.Type;
  75                         }
  76                 }
  77
  78                 public AParametersCollection Parameters {
  79                         get {
  80                                 return parameters;
  81                         }
  82                 }
  83                 #endregion
  84
  85                 public override void Accept (StructuralVisitor visitor)
  86                 {
  87                         visitor.Visit (this);
  88                 }
  89
  90                 public override void ApplyAttributeBuilder (Attribute a, MethodSpec ctor, byte[] cdata, PredefinedAttributes pa)
  91                 {
  92                         if (a.Target == AttributeTargets.ReturnValue) {
  93                                 if (return_attributes == null)
  94                                         return_attributes = new ReturnParameter (this, InvokeBuilder.MethodBuilder, Location);
  95
  96                                 return_attributes.ApplyAttributeBuilder (a, ctor, cdata, pa);
  97                                 return;
  98                         }
  99
 100                         base.ApplyAttributeBuilder (a, ctor, cdata, pa);
 101                 }
 102
 103                 public override AttributeTargets AttributeTargets {
 104                         get {
 105                                 return AttributeTargets.Delegate;
 106                         }
 107                 }
 108
 109                 protected override bool DoDefineMembers ()
 110                 {
 111                         var ctor_parameters = ParametersCompiled.CreateFullyResolved (
 112                                 new [] {
 113                                         new Parameter (new TypeExpression (TypeManager.object_type, Location), "object", Parameter.Modifier.NONE, null, Location),
 114                                         new Parameter (new TypeExpression (TypeManager.intptr_type, Location), "method", Parameter.Modifier.NONE, null, Location)
 115                                 },
 116                                 new [] {
 117                                         TypeManager.object_type,
 118                                         TypeManager.intptr_type
 119                                 }
 120                         );
 121
 122                         Constructor = new Constructor (this, Constructor.ConstructorName,
 123                                 Modifiers.PUBLIC, null, ctor_parameters, null, Location);
 124                         Constructor.Define ();
 125
 126                         //
 127                         // Here the various methods like Invoke, BeginInvoke etc are defined
 128                         //
 129                         // First, call the `out of band' special method for
 130                         // defining recursively any types we need:
 131                         //
 132                         var p = parameters;
 133
 134                         if (!p.Resolve (this))
 135                                 return false;
 136
 137                         //
 138                         // Invoke method
 139                         //
 140
 141                         // Check accessibility
 142                         foreach (var partype in p.Types) {
 143                                 if (!IsAccessibleAs (partype)) {
 144                                         Report.SymbolRelatedToPreviousError (partype);
 145                                         Report.Error (59, Location,
 146                                                 "Inconsistent accessibility: parameter type `{0}' is less accessible than delegate `{1}'",
 147                                                 TypeManager.CSharpName (partype), GetSignatureForError ());
 148                                 }
 149                         }
 150
 151                         ReturnType = ReturnType.ResolveAsTypeTerminal (this, false);
 152                         if (ReturnType == null)
 153                                 return false;
 154
 155                         var ret_type = ReturnType.Type;
 156
 157                         //
 158                         // We don't have to check any others because they are all
 159                         // guaranteed to be accessible - they are standard types.
 160                         //
 161                         if (!IsAccessibleAs (ret_type)) {
 162                                 Report.SymbolRelatedToPreviousError (ret_type);
 163                                 Report.Error (58, Location,
 164                                                   "Inconsistent accessibility: return type `" +
 165                                                   TypeManager.CSharpName (ret_type) + "' is less " +
 166                                                   "accessible than delegate `" + GetSignatureForError () + "'");
 167                                 return false;
 168                         }
 169
 170                         CheckProtectedModifier ();
 171
 172                         if (Compiler.Settings.StdLib && TypeManager.IsSpecialType (ret_type)) {
 173                                 Method.Error1599 (Location, ret_type, Report);
 174                                 return false;
 175                         }
 176
 177                         TypeManager.CheckTypeVariance (ret_type, Variance.Covariant, this);
 178
 179                         InvokeBuilder = new Method (this, null, ReturnType, MethodModifiers, new MemberName (InvokeMethodName), p, null);
 180                         InvokeBuilder.Define ();
 181
 182                         //
 183                         // Don't emit async method for compiler generated delegates (e.g. dynamic site containers)
 184                         //
 185                         if (!IsCompilerGenerated) {
 186                                 DefineAsyncMethods (Parameters.CallingConvention);
 187                         }
 188
 189                         return true;
 190                 }
 191
 192                 void DefineAsyncMethods (CallingConventions cc)
 193                 {
 194                         var iasync_result = Module.PredefinedTypes.IAsyncResult;
 195                         var async_callback = Module.PredefinedTypes.AsyncCallback;
 196
 197                         //
 198                         // It's ok when async types don't exist, the delegate will have Invoke method only
 199                         //
 200                         if (!iasync_result.Define () || !async_callback.Define ())
 201                                 return;
 202
 203                         //
 204                         // BeginInvoke
 205                         //
 206                         ParametersCompiled async_parameters;
 207                         if (Parameters.Count == 0) {
 208                                 async_parameters = ParametersCompiled.EmptyReadOnlyParameters;
 209                         } else {
 210                                 var compiled = new Parameter[Parameters.Count];
 211                                 for (int i = 0; i < compiled.Length; ++i) {
 212                                         var p = parameters[i];
 213                                         compiled[i] = new Parameter (new TypeExpression (parameters.Types[i], Location),
 214                                                 p.Name,
 215                                                 p.ModFlags & (Parameter.Modifier.REF | Parameter.Modifier.OUT),
 216                                                 p.OptAttributes == null ? null : p.OptAttributes.Clone (), Location);
 217                                 }
 218
 219                                 async_parameters = new ParametersCompiled (compiled);
 220                         }
 221
 222                         async_parameters = ParametersCompiled.MergeGenerated (Compiler, async_parameters, false,
 223                                 new Parameter[] {
 224                                         new Parameter (new TypeExpression (async_callback.TypeSpec, Location), "callback", Parameter.Modifier.NONE, null, Location),
 225                                         new Parameter (new TypeExpression (TypeManager.object_type, Location), "object", Parameter.Modifier.NONE, null, Location)
 226                                 },
 227                                 new [] {
 228                                         async_callback.TypeSpec,
 229                                         TypeManager.object_type
 230                                 }
 231                         );
 232
 233                         BeginInvokeBuilder = new Method (this, null,
 234                                 new TypeExpression (iasync_result.TypeSpec, Location), MethodModifiers,
 235                                 new MemberName ("BeginInvoke"), async_parameters, null);
 236                         BeginInvokeBuilder.Define ();
 237
 238                         //
 239                         // EndInvoke is a bit more interesting, all the parameters labeled as
 240                         // out or ref have to be duplicated here.
 241                         //
 242
 243                         //
 244                         // Define parameters, and count out/ref parameters
 245                         //
 246                         ParametersCompiled end_parameters;
 247                         int out_params = 0;
 248
 249                         foreach (Parameter p in Parameters.FixedParameters) {
 250                                 if ((p.ModFlags & Parameter.Modifier.ISBYREF) != 0)
 251                                         ++out_params;
 252                         }
 253
 254                         if (out_params > 0) {
 255                                 Parameter[] end_params = new Parameter[out_params];
 256
 257                                 int param = 0;
 258                                 for (int i = 0; i < Parameters.FixedParameters.Length; ++i) {
 259                                         Parameter p = parameters [i];
 260                                         if ((p.ModFlags & Parameter.Modifier.ISBYREF) == 0)
 261                                                 continue;
 262
 263                                         end_params [param++] = new Parameter (new TypeExpression (p.Type, Location),
 264                                                 p.Name,
 265                                                 p.ModFlags & (Parameter.Modifier.REF | Parameter.Modifier.OUT),
 266                                                 p.OptAttributes == null ? null : p.OptAttributes.Clone (), Location);
 267                                 }
 268
 269                                 end_parameters = new ParametersCompiled (end_params);
 270                         } else {
 271                                 end_parameters = ParametersCompiled.EmptyReadOnlyParameters;
 272                         }
 273
 274                         end_parameters = ParametersCompiled.MergeGenerated (Compiler, end_parameters, false,
 275                                 new Parameter (
 276                                         new TypeExpression (iasync_result.TypeSpec, Location),
 277                                         "result", Parameter.Modifier.NONE, null, Location),
 278                                 iasync_result.TypeSpec);
 279
 280                         //
 281                         // Create method, define parameters, register parameters with type system
 282                         //
 283                         EndInvokeBuilder = new Method (this, null, ReturnType, MethodModifiers, new MemberName ("EndInvoke"), end_parameters, null);
 284                         EndInvokeBuilder.Define ();
 285                 }
 286
 287                 public override void DefineConstants ()
 288                 {
 289                         if (!Parameters.IsEmpty) {
 290                                 parameters.ResolveDefaultValues (this);
 291                         }
 292                 }
 293
 294                 public override void EmitType ()
 295                 {
 296                         if (ReturnType.Type != null) {
 297                                 if (ReturnType.Type == InternalType.Dynamic) {
 298                                         return_attributes = new ReturnParameter (this, InvokeBuilder.MethodBuilder, Location);
 299                                         Module.PredefinedAttributes.Dynamic.EmitAttribute (return_attributes.Builder);
 300                                 } else if (ReturnType.Type.HasDynamicElement) {
 301                                         return_attributes = new ReturnParameter (this, InvokeBuilder.MethodBuilder, Location);
 302                                         Module.PredefinedAttributes.Dynamic.EmitAttribute (return_attributes.Builder, ReturnType.Type, Location);
 303                                 }
 304                         }
 305
 306                         Constructor.ParameterInfo.ApplyAttributes (this, Constructor.ConstructorBuilder);
 307                         Constructor.ConstructorBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 308
 309                         parameters.ApplyAttributes (this, InvokeBuilder.MethodBuilder);
 310                         InvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 311
 312                         if (BeginInvokeBuilder != null) {
 313                                 BeginInvokeBuilder.ParameterInfo.ApplyAttributes (this, BeginInvokeBuilder.MethodBuilder);
 314                                 EndInvokeBuilder.ParameterInfo.ApplyAttributes (this, EndInvokeBuilder.MethodBuilder);
 315
 316                                 BeginInvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 317                                 EndInvokeBuilder.MethodBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 318                         }
 319
 320                         if (OptAttributes != null) {
 321                                 OptAttributes.Emit ();
 322                         }
 323
 324                         base.Emit ();
 325                 }
 326
 327                 protected override TypeExpr[] ResolveBaseTypes (out TypeExpr base_class)
 328                 {
 329                         base_type = TypeManager.multicast_delegate_type;
 330                         base_class = null;
 331                         return null;
 332                 }
 333
 334                 protected override TypeAttributes TypeAttr {
 335                         get {
 336                                 return ModifiersExtensions.TypeAttr (ModFlags, IsTopLevel) |
 337                                         TypeAttributes.Class | TypeAttributes.Sealed |
 338                                         base.TypeAttr;
 339                         }
 340                 }
 341
 342                 public override string[] ValidAttributeTargets {
 343                         get {
 344                                 return attribute_targets;
 345                         }
 346                 }
 347
 348                 //TODO: duplicate
 349                 protected override bool VerifyClsCompliance ()
 350                 {
 351                         if (!base.VerifyClsCompliance ()) {
 352                                 return false;
 353                         }
 354
 355                         parameters.VerifyClsCompliance (this);
 356
 357                         if (!ReturnType.Type.IsCLSCompliant ()) {
 358                                 Report.Warning (3002, 1, Location, "Return type of `{0}' is not CLS-compliant",
 359                                         GetSignatureForError ());
 360                         }
 361                         return true;
 362                 }
 363
 364
 365                 public static MethodSpec GetConstructor (TypeSpec delType)
 366                 {
 367                         var ctor = MemberCache.FindMember (delType, MemberFilter.Constructor (null), BindingRestriction.DeclaredOnly);
 368                         return (MethodSpec) ctor;
 369                 }
 370
 371                 //
 372                 // Returns the "Invoke" from a delegate type
 373                 //
 374                 public static MethodSpec GetInvokeMethod (TypeSpec delType)
 375                 {
 376                         var invoke = MemberCache.FindMember (delType,
 377                                 MemberFilter.Method (InvokeMethodName, 0, null, null),
 378                                 BindingRestriction.DeclaredOnly);
 379
 380                         return (MethodSpec) invoke;
 381                 }
 382
 383                 public static AParametersCollection GetParameters (TypeSpec delType)
 384                 {
 385                         var invoke_mb = GetInvokeMethod (delType);
 386                         return invoke_mb.Parameters;
 387                 }
 388
 389                 //
 390                 // 15.2 Delegate compatibility
 391                 //
 392                 public static bool IsTypeCovariant (ResolveContext rc, Expression a, TypeSpec b)
 393                 {
 394                         //
 395                         // For each value parameter (a parameter with no ref or out modifier), an
 396                         // identity conversion or implicit reference conversion exists from the
 397                         // parameter type in D to the corresponding parameter type in M
 398                         //
 399                         if (a.Type == b)
 400                                 return true;
 401
 402                         if (rc.Module.Compiler.Settings.Version == LanguageVersion.ISO_1)
 403                                 return false;
 404
 405                         return Convert.ImplicitReferenceConversionExists (a, b);
 406                 }
 407
 408                 public static string FullDelegateDesc (MethodSpec invoke_method)
 409                 {
 410                         return TypeManager.GetFullNameSignature (invoke_method).Replace (".Invoke", "");
 411                 }
 412
 413                 public Expression InstanceExpression {
 414                         get {
 415                                 return instance_expr;
 416                         }
 417                         set {
 418                                 instance_expr = value;
 419                         }
 420                 }
 421         }
 422
 423         //
 424         // Base class for `NewDelegate' and `ImplicitDelegateCreation'
 425         //
 426         public abstract class DelegateCreation : Expression, OverloadResolver.IErrorHandler
 427         {
 428                 protected MethodSpec constructor_method;
 429                 protected MethodGroupExpr method_group;
 430
 431                 public static Arguments CreateDelegateMethodArguments (AParametersCollection pd, TypeSpec[] types, Location loc)
 432                 {
 433                         Arguments delegate_arguments = new Arguments (pd.Count);
 434                         for (int i = 0; i < pd.Count; ++i) {
 435                                 Argument.AType atype_modifier;
 436                                 switch (pd.FixedParameters [i].ModFlags) {
 437                                 case Parameter.Modifier.REF:
 438                                         atype_modifier = Argument.AType.Ref;
 439                                         break;
 440                                 case Parameter.Modifier.OUT:
 441                                         atype_modifier = Argument.AType.Out;
 442                                         break;
 443                                 default:
 444                                         atype_modifier = 0;
 445                                         break;
 446                                 }
 447
 448                                 delegate_arguments.Add (new Argument (new TypeExpression (types [i], loc), atype_modifier));
 449                         }
 450
 451                         return delegate_arguments;
 452                 }
 453
 454                 public override Expression CreateExpressionTree (ResolveContext ec)
 455                 {
 456                         MemberAccess ma = new MemberAccess (new MemberAccess (new QualifiedAliasMember ("global", "System", loc), "Delegate", loc), "CreateDelegate", loc);
 457
 458                         Arguments args = new Arguments (3);
 459                         args.Add (new Argument (new TypeOf (new TypeExpression (type, loc), loc)));
 460
 461                         if (method_group.InstanceExpression == null)
 462                                 args.Add (new Argument (new NullLiteral (loc)));
 463                         else
 464                                 args.Add (new Argument (method_group.InstanceExpression));
 465
 466                         args.Add (new Argument (method_group.CreateExpressionTree (ec)));
 467                         Expression e = new Invocation (ma, args).Resolve (ec);
 468                         if (e == null)
 469                                 return null;
 470
 471                         e = Convert.ExplicitConversion (ec, e, type, loc);
 472                         if (e == null)
 473                                 return null;
 474
 475                         return e.CreateExpressionTree (ec);
 476                 }
 477
 478                 protected override Expression DoResolve (ResolveContext ec)
 479                 {
 480                         constructor_method = Delegate.GetConstructor (type);
 481
 482                         var invoke_method = Delegate.GetInvokeMethod (type);
 483
 484                         Arguments arguments = CreateDelegateMethodArguments (invoke_method.Parameters, invoke_method.Parameters.Types, loc);
 485                         method_group = method_group.OverloadResolve (ec, ref arguments, this, OverloadResolver.Restrictions.CovariantDelegate);
 486                         if (method_group == null)
 487                                 return null;
 488
 489                         var delegate_method = method_group.BestCandidate;
 490
 491                         if (TypeManager.IsNullableType (delegate_method.DeclaringType)) {
 492                                 ec.Report.Error (1728, loc, "Cannot create delegate from method `{0}' because it is a member of System.Nullable<T> type",
 493                                         delegate_method.GetSignatureForError ());
 494                                 return null;
 495                         }
 496
 497                         Invocation.IsSpecialMethodInvocation (ec, delegate_method, loc);
 498
 499                         ExtensionMethodGroupExpr emg = method_group as ExtensionMethodGroupExpr;
 500                         if (emg != null) {
 501                                 method_group.InstanceExpression = emg.ExtensionExpression;
 502                                 TypeSpec e_type = emg.ExtensionExpression.Type;
 503                                 if (TypeManager.IsValueType (e_type)) {
 504                                         ec.Report.Error (1113, loc, "Extension method `{0}' of value type `{1}' cannot be used to create delegates",
 505                                                 delegate_method.GetSignatureForError (), TypeManager.CSharpName (e_type));
 506                                 }
 507                         }
 508
 509                         TypeSpec rt = delegate_method.ReturnType;
 510                         Expression ret_expr = new TypeExpression (rt, loc);
 511                         if (!Delegate.IsTypeCovariant (ec, ret_expr, invoke_method.ReturnType)) {
 512                                 Error_ConversionFailed (ec, delegate_method, ret_expr);
 513                         }
 514
 515                         if (delegate_method.IsConditionallyExcluded (loc)) {
 516                                 ec.Report.SymbolRelatedToPreviousError (delegate_method);
 517                                 MethodOrOperator m = delegate_method.MemberDefinition as MethodOrOperator;
 518                                 if (m != null && m.IsPartialDefinition) {
 519                                         ec.Report.Error (762, loc, "Cannot create delegate from partial method declaration `{0}'",
 520                                                 delegate_method.GetSignatureForError ());
 521                                 } else {
 522                                         ec.Report.Error (1618, loc, "Cannot create delegate with `{0}' because it has a Conditional attribute",
 523                                                 TypeManager.CSharpSignature (delegate_method));
 524                                 }
 525                         }
 526
 527                         var expr = method_group.InstanceExpression;
 528                         if (expr != null && (expr.Type.IsGenericParameter || !TypeManager.IsReferenceType (expr.Type)))
 529                                 method_group.InstanceExpression = new BoxedCast (expr, TypeManager.object_type);
 530
 531                         eclass = ExprClass.Value;
 532                         return this;
 533                 }
 534
 535                 public override void Emit (EmitContext ec)
 536                 {
 537                         if (method_group.InstanceExpression == null)
 538                                 ec.Emit (OpCodes.Ldnull);
 539                         else
 540                                 method_group.InstanceExpression.Emit (ec);
 541
 542                         var delegate_method = method_group.BestCandidate;
 543
 544                         // Any delegate must be sealed
 545                         if (!delegate_method.DeclaringType.IsDelegate && delegate_method.IsVirtual && !method_group.IsBase) {
 546                                 ec.Emit (OpCodes.Dup);
 547                                 ec.Emit (OpCodes.Ldvirtftn, delegate_method);
 548                         } else {
 549                                 ec.Emit (OpCodes.Ldftn, delegate_method);
 550                         }
 551
 552                         ec.Emit (OpCodes.Newobj, constructor_method);
 553                 }
 554
 555                 void Error_ConversionFailed (ResolveContext ec, MethodSpec method, Expression return_type)
 556                 {
 557                         var invoke_method = Delegate.GetInvokeMethod (type);
 558                         string member_name = method_group.InstanceExpression != null ?
 559                                 Delegate.FullDelegateDesc (method) :
 560                                 TypeManager.GetFullNameSignature (method);
 561
 562                         ec.Report.SymbolRelatedToPreviousError (type);
 563                         ec.Report.SymbolRelatedToPreviousError (method);
 564                         if (ec.Module.Compiler.Settings.Version == LanguageVersion.ISO_1) {
 565                                 ec.Report.Error (410, loc, "A method or delegate `{0} {1}' parameters and return type must be same as delegate `{2} {3}' parameters and return type",
 566                                         TypeManager.CSharpName (method.ReturnType), member_name,
 567                                         TypeManager.CSharpName (invoke_method.ReturnType), Delegate.FullDelegateDesc (invoke_method));
 568                                 return;
 569                         }
 570
 571                         if (return_type == null) {
 572                                 ec.Report.Error (123, loc, "A method or delegate `{0}' parameters do not match delegate `{1}' parameters",
 573                                         member_name, Delegate.FullDelegateDesc (invoke_method));
 574                                 return;
 575                         }
 576
 577                         ec.Report.Error (407, loc, "A method or delegate `{0} {1}' return type does not match delegate `{2} {3}' return type",
 578                                 return_type.GetSignatureForError (), member_name,
 579                                 TypeManager.CSharpName (invoke_method.ReturnType), Delegate.FullDelegateDesc (invoke_method));
 580                 }
 581
 582                 public static bool ImplicitStandardConversionExists (ResolveContext ec, MethodGroupExpr mg, TypeSpec target_type)
 583                 {
 584                         if (target_type == TypeManager.delegate_type || target_type == TypeManager.multicast_delegate_type)
 585                                 return false;
 586
 587                         var invoke = Delegate.GetInvokeMethod (target_type);
 588
 589                         Arguments arguments = CreateDelegateMethodArguments (invoke.Parameters, invoke.Parameters.Types, mg.Location);
 590                         return mg.OverloadResolve (ec, ref arguments, null, OverloadResolver.Restrictions.CovariantDelegate | OverloadResolver.Restrictions.ProbingOnly) != null;
 591                 }
 592
 593                 #region IErrorHandler Members
 594
 595                 bool OverloadResolver.IErrorHandler.AmbiguousCandidates (ResolveContext ec, MemberSpec best, MemberSpec ambiguous)
 596                 {
 597                         return false;
 598                 }
 599
 600                 bool OverloadResolver.IErrorHandler.ArgumentMismatch (ResolveContext rc, MemberSpec best, Argument arg, int index)
 601                 {
 602                         Error_ConversionFailed (rc, best as MethodSpec, null);
 603                         return true;
 604                 }
 605
 606                 bool OverloadResolver.IErrorHandler.NoArgumentMatch (ResolveContext rc, MemberSpec best)
 607                 {
 608                         Error_ConversionFailed (rc, best as MethodSpec, null);
 609                         return true;
 610                 }
 611
 612                 bool OverloadResolver.IErrorHandler.TypeInferenceFailed (ResolveContext rc, MemberSpec best)
 613                 {
 614                         return false;
 615                 }
 616
 617                 #endregion
 618         }
 619
 620         //
 621         // Created from the conversion code
 622         //
 623         public class ImplicitDelegateCreation : DelegateCreation
 624         {
 625                 ImplicitDelegateCreation (TypeSpec t, MethodGroupExpr mg, Location l)
 626                 {
 627                         type = t;
 628                         this.method_group = mg;
 629                         loc = l;
 630                 }
 631
 632                 static public Expression Create (ResolveContext ec, MethodGroupExpr mge,
 633                                                  TypeSpec target_type, Location loc)
 634                 {
 635                         ImplicitDelegateCreation d = new ImplicitDelegateCreation (target_type, mge, loc);
 636                         return d.DoResolve (ec);
 637                 }
 638         }
 639
 640         //
 641         // A delegate-creation-expression, invoked from the `New' class
 642         //
 643         public class NewDelegate : DelegateCreation
 644         {
 645                 public Arguments Arguments;
 646
 647                 //
 648                 // This constructor is invoked from the `New' expression
 649                 //
 650                 public NewDelegate (TypeSpec type, Arguments Arguments, Location loc)
 651                 {
 652                         this.type = type;
 653                         this.Arguments = Arguments;
 654                         this.loc  = loc;
 655                 }
 656
 657                 protected override Expression DoResolve (ResolveContext ec)
 658                 {
 659                         if (Arguments == null || Arguments.Count != 1) {
 660                                 ec.Report.Error (149, loc, "Method name expected");
 661                                 return null;
 662                         }
 663
 664                         Argument a = Arguments [0];
 665                         if (!a.ResolveMethodGroup (ec))
 666                                 return null;
 667
 668                         Expression e = a.Expr;
 669
 670                         AnonymousMethodExpression ame = e as AnonymousMethodExpression;
 671                         if (ame != null && ec.Module.Compiler.Settings.Version != LanguageVersion.ISO_1) {
 672                                 e = ame.Compatible (ec, type);
 673                                 if (e == null)
 674                                         return null;
 675
 676                                 return e.Resolve (ec);
 677                         }
 678
 679                         method_group = e as MethodGroupExpr;
 680                         if (method_group == null) {
 681                                 if (e.Type == InternalType.Dynamic) {
 682                                         e = Convert.ImplicitConversionRequired (ec, e, type, loc);
 683                                 } else if (!e.Type.IsDelegate) {
 684                                         e.Error_UnexpectedKind (ec, ResolveFlags.MethodGroup | ResolveFlags.Type, loc);
 685                                         return null;
 686                                 }
 687
 688                                 //
 689                                 // An argument is not a method but another delegate
 690                                 //
 691                                 method_group = new MethodGroupExpr (Delegate.GetInvokeMethod (e.Type), e.Type, loc);
 692                                 method_group.InstanceExpression = e;
 693                         }
 694
 695                         return base.DoResolve (ec);
 696                 }
 697         }
 698
 699         //
 700         // Invocation converted to delegate Invoke call
 701         //
 702         class DelegateInvocation : ExpressionStatement
 703         {
 704                 readonly Expression InstanceExpr;
 705                 Arguments arguments;
 706                 MethodSpec method;
 707
 708                 public DelegateInvocation (Expression instance_expr, Arguments args, Location loc)
 709                 {
 710                         this.InstanceExpr = instance_expr;
 711                         this.arguments = args;
 712                         this.loc = loc;
 713                 }
 714
 715                 public override Expression CreateExpressionTree (ResolveContext ec)
 716                 {
 717                         Arguments args = Arguments.CreateForExpressionTree (ec, this.arguments,
 718                                 InstanceExpr.CreateExpressionTree (ec));
 719
 720                         return CreateExpressionFactoryCall (ec, "Invoke", args);
 721                 }
 722
 723                 protected override Expression DoResolve (ResolveContext ec)
 724                 {
 725                         TypeSpec del_type = InstanceExpr.Type;
 726                         if (del_type == null)
 727                                 return null;
 728
 729                         //
 730                         // Do only core overload resolution the rest of the checks has been
 731                         // done on primary expression
 732                         //
 733                         method = Delegate.GetInvokeMethod (del_type);
 734                         var res = new OverloadResolver (new MemberSpec[] { method }, OverloadResolver.Restrictions.DelegateInvoke, loc);
 735                         var valid = res.ResolveMember<MethodSpec> (ec, ref arguments);
 736                         if (valid == null && !res.BestCandidateIsDynamic)
 737                                 return null;
 738
 739                         type = method.ReturnType;
 740                         eclass = ExprClass.Value;
 741                         return this;
 742                 }
 743
 744                 public override void Emit (EmitContext ec)
 745                 {
 746                         //
 747                         // Invocation on delegates call the virtual Invoke member
 748                         // so we are always `instance' calls
 749                         //
 750                         Invocation.EmitCall (ec, InstanceExpr, method, arguments, loc);
 751                 }
 752
 753                 public override void EmitStatement (EmitContext ec)
 754                 {
 755                         Emit (ec);
 756                         //
 757                         // Pop the return value if there is one
 758                         //
 759                         if (type != TypeManager.void_type)
 760                                 ec.Emit (OpCodes.Pop);
 761                 }
 762
 763                 public override System.Linq.Expressions.Expression MakeExpression (BuilderContext ctx)
 764                 {
 765                         return Invocation.MakeExpression (ctx, InstanceExpr, method, arguments);
 766                 }
 767         }
 768 }